Embodiments of the subject matter disclosed herein generally relate to hydraulic power recovery turbine systems. More specifically, the present disclosure concerns improvements in the bearing/clutch arrangement connecting the hydraulic power recovery turbine to an electric motor, a centrifugal pump, or a rotary equipment in general.
Concerns on the environmental impact of energy production and consumption are fostering the research for improving the energy efficiency of industrial plants, systems and processes in various ways. In many industrial plants, energy is available e.g. in the form of waste heat, pressure energy or fluid head or the like. In recent years efforts have been made to exploit this kind of energy which was previously simply dissipated.
Hydraulic power recovery turbines are used in several installations, plants and systems for recovering energy from a flow of pressurized liquid. Generally speaking, a hydraulic power recovery turbine is a machine used to recover power from a liquid stream by reducing the pressure thereof. A common type of hydraulic power recovery turbine is a reverse-rotating centrifugal pump that recovers power from a high pressure process liquid by reducing its pressure that will otherwise be wasted across throttle valves.
Traditionally, hydraulic power recovery turbines are used in plants where a large amount of fluid energy is dissipated in valves or other throttling devices. Power recovery is achieved using the fluid pressure and, more in general, a static head available in a plant, to drive the hydraulic power recovery turbine and obtaining useful mechanical power on the output shaft thereof. The power recovered by the hydraulic power recovery turbine is usually utilized to drive auxiliaries, such as a pump, or to reduce power absorbed from the electric grid, e.g. by supplementing mechanical energy to a driving shaft of an electric motor which drives a pump.
In some applications, the hydraulic power recovery turbine is utilized to drive an electric generator, thus converting the useful mechanical power available on the output shaft thereof into electric power.
For usefully exploiting pressure energy contained in high-pressure liquids, hydraulic power recovery turbines are often used in combination with electric motors, in order to exploit for example the power developed by a flow of liquid available in an industrial system. The power generated by the liquid flow is converted into mechanical power by the hydraulic power recovery turbine and the useful mechanical power available on the shaft of the hydraulic power recovery turbine is used for example to drive a load in combination with an electric motor.
FIG. 1 illustrates an installation according to the current art of a pump driven by an electric motor in combination with a hydraulic power recovery turbine, which is designed for recovering power from a fluid flow.
The system of FIG. 1, labeled 100 as a whole, comprises rotary equipment, for example a pump 101, which is driven into rotation by an electric motor 103. A pump shaft 101S is connected to a first end of a shaft 103S of the electric motor 103 through a gearbox 105. Joints, for example flexible shaft couplings 107, 109 can be provided between the gearbox 105 and the pump 101 and between the gearbox 105 and the first end of shaft 103S of the electric motor 103, respectively. A second end of the electric motor shaft 103S is connected to a hydraulic power recovery turbine 111.
The connection between the hydraulic power recovery turbine 111 and the electric motor shaft 103S requires a clutch 113, which is housed in a housing 115 supported on a base plate 117, also supporting the remaining rotary machinery, namely the rotary equipment or rotary load 101, the electric motor 103 and the hydraulic power recovery turbine 111.
A first shaft coupling 119 is arranged between the electric motor shaft 103S and the clutch 113. A second shaft coupling 121 is arranged between the clutch 113 and a shaft 111S of the hydraulic power recovery turbine 111.
The hydraulic power recovery turbine 111 is provided with a turbine inlet 123 and a turbine outlet 125. The turbine inlet 123 and the turbine outlet 125 are connected to a hydraulic circuit (not shown), where through a fluid can flow. The hydraulic power recovery turbine 111 converts the power of the fluid flowing in the hydraulic circuit into useful mechanical power available on the turbine shaft 111S.
The operation of the system 100 is as follows. Under normal operating conditions, the electric motor 103 generates on the electric motor shaft 103S the entire mechanical power required for driving the rotary equipment 101 into rotation, for example for pumping a fluid which enters the pump 101 through a suction manifold 102 and is delivered by the pump 101 through a delivery manifold 104.
If a fluid flow is available in the hydraulic circuit connected to the turbine inlet 123 and the turbine outlet 125, the fluid flow is used for driving the hydraulic power recovery turbine 111 into rotation. When the rotary speed of the hydraulic power recovery turbine 111 becomes identical to the rotary speed of the electric motor 103, the clutch 113 is engaged, so that useful mechanical power can be delivered by the turbine shaft 111S to the electric motor shaft 103S. The mechanical power available from the hydraulic power recovery turbine 111 reduces the electric power consumed by the electric motor 103 for driving the rotary equipment 101.
The rotary machine arrangement provided on the baseplate 117 is particularly cumbersome and has a long footprint, in particular due to the quite large number of ancillary equipment arranged between each rotating machine 111, 103 and 101, in particular shaft couplings 107, 109, 119, 121, gearbox 105 and clutch 113.